Anthotype

The anthotype is the process Herschel spent more effort on than the cyanotype and abandoned, and it is worth an atlas entry for the reason it failed rather than for anything it can do. Its defect is structural, not practical, and asking a process whether it can be stopped turns out to be a better question than asking how fast it is. The Part I lesson establishes it.

The chemistry

Petals are crushed in alcohol, the dye is painted on paper, and a print is made by laying an object or an engraving on the sheet and letting sunlight bleach the exposed dye. The image is the dye that survived.

Read what that arrangement does and does not have. There is no metal, no crystal and no amplification, so it belongs with heliography rather than with any silver process in what light has to accomplish unaided — and unlike heliography, there is no development step at all, not even a solvent. It is the purest possible case of printing out: light does everything, and there is nothing afterwards.

⚗Why no fixer can exist for it, and what that teaches

A fixer works by removing or converting the light-sensitive material that is not the image. In a salted paper print the image silver is insoluble and so is the unused silver halide beside it, which is why thiosulfate is needed to tell them apart. In a cyanotype the image is insoluble and the unused sensitiser is soluble, so water finishes it.

Here the image is the light-sensitive material. There is nothing to remove and nothing to convert; the same reaction that made the picture goes on making it, in the same direction, whenever the sheet is looked at. That is not a process waiting for a better fixer. It is a process for which the word does not apply.

The one durable result Herschel got from it was a principle, and Ware records that it came out of over a thousand tests: a dye is bleached fastest by the light of its complementary colour. That is a real photochemical finding, and it is the reason the effort was not wasted.

Historical workflow

Paint, dry, contact-print in sunlight for days or weeks, and stop when it looks right — after which the print begins to go.

Herschel wanted two things from it that his other processes could not give. It is positive-working, which he wanted; and it produces colour, which he wanted more. He told the British Association in 1841 that it held out “no slight hope of a solution of the problem of a photographic representation of natural objects in their proper colours.”

It sits in his research programme immediately before the change of tack that produced the siderotypes. In the spring of 1842 he moved from unstable organic dyes to deeply coloured inorganic ones, and within a fortnight had the cyanotype, the argentotype, the chrysotype and the kelainotype. The anthotype is what he was doing instead, for three years, and the contrast between the two programmes is the most instructive thing about it.

The image

Colour, which is the whole attraction, and the course states no more about it than that: the hue is whatever plant was used, and the image is the surviving dye bleaching towards the paper where light fell.

What this atlas cannot state. No source read here gives a tonal scale, a maximum density, a characteristic surface beyond “dye on paper”, or an identification signature. Those fields are left empty above rather than filled with a plausible guess.

Permanence

None, and the absence is definitional rather than a defect of workmanship. Every other process in this atlas can be made more or less permanent by processing it better. This one cannot be made permanent at all: displaying it destroys it, and storing it in the dark is the only measure available, which is the same custodial answer the Bayard direct positive gets for a different reason.

That is worth setting against the two neighbouring answers Part I works through. Talbot’s halide treatments stabilise — they leave the salt in the sheet with its reactivity turned down, which is a rate rather than an end point. Herschel’s thiosulfate washes out — an end point. The anthotype has neither, and the course’s own summary of the case is that whether a process can be stopped is a better question to ask of it than how fast it is.

Hazards

The least hazardous entry in this atlas. Plant material, small quantities of alcohol for the extraction, paper and sunlight. Against the rubric that is Level A on every criterion: nothing classified beyond irritant at the quantities handled, no heating above 50 °C, no mains work, and a waste stream of dilute plant dye.

Two cautions belong to the plants rather than to the photography, and the course names them without being able to resolve them. Not every plant is benign, and the course has read no source assessing the toxicity of particular anthotype species. And an extraction in alcohol is still a volatile organic solvent, which the rubric permits at Level A only in small quantities.

Where the course teaches it

In Part I, as history, and in no part as a practice — and that is now a settled fact rather than an open question.

Herschel’s page teaches it, in the section “1842: from flower juice to Prussian blue”, and it teaches it as the failure that produced the cyanotype. Petals crushed in alcohol, the dye painted on paper, an engraving laid on top and sunlight left to bleach what it can reach. Positive-working and in colour, which is what Herschel wanted; over a thousand tests; almost unusably slow, at days or weeks; and unfixable, because the light that makes the image goes on destroying it. The one durable result was a principle — a dye is bleached fastest by the light of its complementary colour — and in the spring of 1842 Herschel gave up on unstable organic dyes for deeply coloured inorganic ones, which is where the cyanotype comes from.

Both parts that might have owned it are written, and neither took it. The register that plans this atlas records the owning part as provisional, because design-history.json openQuestions[10] never settled whether the anthotype belonged to Part I or to Part XXI. Part XXI is now written and does not carry it: its variants lesson covers cyanotype off paper, the formulations, and the variants studied and not reproduced, and the anthotype is in none of them. Part I carries it and gives no procedure. So the open question has been answered by omission rather than by decision, and this entry states that as the present position instead of promising a page that nobody has undertaken to write.

This atlas does not manufacture an owner, and it should not: no part of the course teaches the anthotype as a practice, and saying otherwise would be inventing a route. What a reader who wants one should know is that the process needs no chemistry a page could get wrong — it needs plants, alcohol, paper and weeks of sun — and that the reason it is not a lab is the same reason Herschel abandoned it, which the Herschel page argues at length: a process that cannot be stopped is not a process you can be taught to control. That is a better question to ask of any process than how fast it is.

The reason this page exists at all is that Herschel’s page already names anthotype in its processes: list, so a reader following that reference landed on nothing. What Part I does with it is a single argument, and it is the one this entry is organised around: the anthotype gave Herschel colour and a positive and could not be stopped, and three years later the same man made a process that gives one blue and no positive and finishes in plain water. The second one is still being practised.